Quick disconnect couplings have been in use numerous years and in general they comprise two valve members that are adapted to be coupled together whose valves are automatically opened to permit fluid flow through when they are connected and are automatically closed when the valve members are disconnected or no longer coupled together. Such couplings are particularly useful in transferring a liquid to or from one container to another such as in fueling or refueling operations associated with rockets and spacecraft.
Unfortunately, if one or both such valves should malfunction or remain open when the coupled valve members are disconnected this can result in the rapid draining of the fluid contents in the adjacent container through the defective valve. Such an incident can have serious consequences since fluids used with such quick disconnects are in many cases highly corrosive, toxic, inflammable, or explosive or a combination of these. In fact, the malfunctioning of a quick disconnect associated with a Titan missile resulted in the destruction of the missile, its silo, and the serious injury and death of one of the individuals involved in draining oxidizer from the missile. Consequently, it is imperative that quick disconnects have valves that function properly to prevent leaking when the valve members are being disconnected.
Quick disconnect valves can malfunction when something in the fluid passing through the valve lodges in the valve causing it to remain fully or partially open when the valve is disconnected from the other mating valve. This, of course, can result in the leaking of fluid with potentially serious consequences. Also, if the valve seat or valve sealing surfaces are defective this can also result in leaking of the valve.
Attempts to eliminate these problems have been made in the past. Some of these have involved the use of multiple seals in a single poppet. This solution is satisfactory in the case where only one of the seals is defective or becomes damaged. However, if a contaminant particle in the fluid lodges under the poppet and prevents it from reaching its seated position neither one of the seals will function properly.
Another attempted solution has been to add a complete additional valve in series with the quick disconnect valves. While this arrangement appears to function satisfactorily from a safety view point, it increases substantially the amount of spillage (volume between the two valves) and it adds substantially to the complexity of the valve system, to its weight and, of course, to its cost. Consequently, such a solution would not be acceptable for many situations particularly those that are to be used in space or military operations or where cost is a significant consideration.
This invention overcomes these problems associated with previous quick disconnect type valve systems. With this redundant valve disconnect coupling invention it is almost impossible for at least one the valves not to close to stop all fluid flow through the valves when the coupling is disconnected. The redundant valve disconnect coupling invention has two separate independent valves in each coupling half that are nevertheless operated together by the single action of coupling the valves together or by disconnecting them. Consequently, even if one poppet should be stuck open the coupling half will still not leak in view of the closure of the other separate totally independent valve. Each coupling half also has three independent fluid sealing surfaces in the mating (interface) area so that the failure of one surface such as by a scratch, etc. will not affect the others. Finally, this disconnect coupling design offers the flexibility of being capable of mating under a rather large misalignment and offset while maintaining all other capabilities intact.